Semiconductor device having stacked substrates with protruding and recessed electrode connection

ABSTRACT

A first substrate with a penetration electrode formed thereon is stacked on a second substrate with a protruding electrode formed thereon. The penetration electrode has a recessed portion. The substrates are stacked with the protruding electrode entered in the recessed portion. A distal width of the protruding electrode is smaller than an opening width of the recessed portion.

BACKGROUND

1. Technical Field

The present invention relates to a semiconductor device, and a sensorand electronic device having a semiconductor device.

2. Related Art

A semiconductor device is known in which semiconductor substrates havinga penetration electrode formed therein are stacked, with the top andbottom semiconductor substrates electrically connected with each othervia the penetration electrode.

In the related art, for example, as described in Japanese Patent No.4,441,328, a method including providing a penetration electrode in onesemiconductor substrate, providing a protruding electrode on the othersemiconductor substrate, pressing the protruding electrode into apenetration hole and thus plastically deforming the protrudingelectrode, and electrically connecting the top and bottom semiconductorsubstrates in a caulked state, is known.

However, the semiconductor device described in Japanese Patent No.4,441,328 has a problem that the semiconductor substrate cracks when theprotruding electrode is pressed into the penetration hole of thesemiconductor substrate.

SUMMARY

An advantage of some aspects of the invention is to solve at least apart of the problems described above, and the invention can beimplemented as the following forms or application examples.

Application Example 1

This application example of the invention is directed to a semiconductordevice including a first substrate having a main surface and a backsurface situated opposite to each other, and a second substrate stackedon the first substrate and having a main surface and aback surfacesituated opposite to each other. The first substrate includes apenetration hole which penetrates the first substrate in a direction ofthickness thereof, a penetration electrode formed inside the penetrationhole, and a first electrode formed on the main surface. The secondsubstrate includes a second electrode formed on the main surface of thesecond substrate, and a protruding electrode arranged on the secondelectrode and protruding from the main surface of the second substrate.The penetration electrode has a recessed portion on the back surfaceside. A bottom part of the recessed portion is situated toward the mainsurface from the back surface of the first substrate. The penetrationelectrode continues to the first electrode arranged on the main surfacefrom the back surface of the first substrate. The first substrate andthe second substrate are stacked on each other with the protrudingelectrode entered in the recessed portion. An opening width a of therecessed portion and a distal width b of the protruding electrode are ina relation of a>b.

According to this application example, since the distal width of theprotruding electrode formed on the second substrate is smaller than theopening width of the recessed portion formed on the first substrate, theprotruding electrode can easy enter the recessed portion when the firstsubstrate and the second substrate are stacked on each other, and thesubstrates can be connected without being damaged.

Application Example 2

In the semiconductor device of the above application example, it ispreferable that a depth c of the recessed portion in the first substrateand a height d of the protruding electrode on the second substrate arein a relation of c<d.

According to this application example, since the height of theprotruding electrode is greater than the depth of the recessed portion,an appropriate space can be maintained between the first substrate andthe second substrate, and reliability of connection between the firstsubstrate and the second substrate can be improved.

Application Example 3

In the semiconductor device of the above application example, it ispreferable that the recessed portion in the first substrate has anopening expanding toward the back surface from the bottom part.

According to this application example, since the recessed portionexpands toward the back surface from the bottom part, the protrudingelectrode can enter the recessed portion more easily at the time ofstacking, and the first substrate and the second substrate can beconnected with each other without damaging the substrates.

Application Example 4

In the semiconductor device of the above application example, it ispreferable that an insulating film is formed on an inner wall of thepenetration hole in the first substrate, the penetration electrodehaving a conductor layer is situated on the inner side of the insulatingfilm, the recessed portion is arranged in the conductor layer, theconductor layer is made of two or more kinds of material, a surface ofthe recessed portion on the back surface side is made of a materialhaving the lowest melting point, and the material with the low meltingpoint and the protruding electrode formed on the second substrate arejoined by metal-metal junction.

According to this application example, since the conductor layer is madeof two or more kinds of material and the surface of the recessed portionon the back surface side is made of a material having the lowest meltingpoint, metal-metal junction with the protruding electrode can berealized at a lower temperature and thermal stress can be reduced.Therefore, reliability of connection between the first substrate and thesecond substrate can be improved.

Application Example 5

In the semiconductor device of the above application example, it ispreferable that the material with the low melting point is a brazingmaterial.

According to this application example, since a brazing material is used,metal-metal junction can be easily carried out and therefore reliabilityof connection between the first substrate and the second substrate canbe improved.

Application Example 6

In the semiconductor device of the above application example, it ispreferable that the distal width b of the protruding electrode formed onthe second electrode of the second substrate and a width e of theprotruding electrode on the side of the second electrode are in arelation of b<e.

According to this application example, since the width on the secondelectrode side is greater than the distal width of the protrudingelectrode, strength of the protruding electrode can be improved even ifthe distal width is small. Therefore, reliability of connection betweenthe first substrate and the second substrate can be improved.

Application Example 7

This application example of the invention is directed to a sensorincluding the semiconductor device of the above application example.

According to this application example, a highly reliable sensor can beprovided since the semiconductor device is installed therein.

Application Example 8

This application example of the invention is directed to an electronicdevice including the semiconductor device of the above applicationexample.

According to this application example, a highly reliable electronicdevice can be provided since the electronic device includes thesemiconductor device.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIGS. 1A to 1D are sectional views illustrating a process ofmanufacturing a first substrate in Embodiment 1.

FIGS. 2A to 2C are sectional view illustrating the process ofmanufacturing the first substrate in Embodiment 1.

FIG. 3 is a sectional view illustrating a process of manufacturing asecond substrate in Embodiment 1.

FIG. 4 shows the relation between a penetration electrode and aprotruding electrode in Embodiment 1.

FIG. 5 shows the state where the first substrate and the secondsubstrate are stacked in Embodiment 1.

FIG. 6 shows the state where semiconductor substrates are stacked inEmbodiment 2.

FIG. 7 shows the shape of the protruding electrode in Modification 1.

FIG. 8 shows the state where the first substrate and the secondsubstrate are stacked in Modification 1.

FIG. 9 shows another example of the state where the substrates arestacked in Modification 1.

FIGS. 10A and 10B show a sensor according to an application ofembodiment.

FIG. 11 shows an electronic device according to an application ofembodiment.

FIG. 12 shows another electronic device according to an application ofembodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the invention will be described withreference to the drawings. In the drawings, in order to show each layeror member in recognizable sizes, each layer or member is not drawn toactual scale.

Embodiment 1

FIGS. 1A to 1D and FIGS. 2A to 2C are sectional views illustrating aprocess of manufacturing a first substrate of this embodiment. FIG. 3 isa sectional view illustrating a process of manufacturing a secondsubstrate of this embodiment.

In this embodiment, a semiconductor substrate 10 is used as a firstsubstrate. The semiconductor substrate 10 shown in FIG. 1A is asemiconductor wafer but the semiconductor substrate 10 may be asemiconductor chip. In the semiconductor substrate 10, at least oneintegrated circuit (plural on a semiconductor wafer, or one on asemiconductor chip) (for example, a circuit having a transistor and amemory (not shown)) is formed on a first surface 12 as a main surface.On the semiconductor substrate 10, electrodes (for example, pads) 14 asplural first electrodes are formed. Each electrode 14 is electricallyconnected to the integrated circuit. Each electrode 14 may be made ofaluminum (Al) or the like. The surface shape of the electrode 14 is notparticularly limited but the shape is often rectangular. If thesemiconductor substrate 10 is a semiconductor wafer, two or more (onegroup of) electrodes 14 are formed in each area that forms pluralsemiconductor chips.

On the semiconductor substrate 10, one or more layers of passivationfilm 16 are formed. The passivation film 16 can be made of, for example,SiO₂, SiN, polyimde resin or the like. After the passivation film 16 isformed to cover the surface of the electrode 14, a portion of thepassivation film 16 may be etched to expose a portion of the electrode14. Either of dry etching and wet etching may be used for this etching.In etching the passivation film 16, the surface of the electrode 14 maybe etched.

In this embodiment, a penetration hole 21 is formed to reach aninsulating layer 15 on the electrode 14 from a second surface (surfaceopposite to the first surface 12) 20 which is a back surface of thesemiconductor substrate 10, as shown in FIG. 1A. Etching (dry etching orwet etching) may be used to form the penetration hole 21. Etching may becarried out after a patterned resist (not shown) is formed bylithography. Alternatively, a laser (for example, CO₂ laser, YAG laseror the like) may be used to form the penetration hole 21. The insulatinglayer 15 may be, for example, SiO₂ or SiN.

Next, an insulating film 22 is formed on an inner surface of thepenetration hole 21, as shown in FIG. 1B. The insulating film 22 may bean oxide film. For example, if the base material of the semiconductorsubstrate 10 is Si, the insulating film may be SiO₂ or SiN or may be aresin. An insulating film may also be formed on the second surface 20and on a bottom part of the penetration hole 21 (on the insulating layer15).

Subsequently, an opening 23 continuing from the bottom part of thepenetration hole 21 to the electrode 14 is formed, as shown in FIG. 1C.The opening 23 may be smaller than the penetration hole 21. Etching (dryetching or wet etching) may be used to form the opening 23. Etching maybe carried out after a patterned resist (not shown) is formed on theinsulating film 22 by lithography.

A conductor layer 25 is formed in the penetration hole 21, as shown inFIG. 1D. Sputtering may be used to form the conductor layer 25. Theconductor layer 25 may include at least a barrier layer. The barrierlayer is adapted to prevent the material of a layer formed thereon frombeing dispersed into the semiconductor substrate 10 (for example, Si).The barrier layer may be made of, for example, TiW or TiN. A conductorlayer may also be formed on the second surface 20 and the inner surface(inner side and bottom part) of the penetration hole 21. The conductorlayer 25 may also include a seed layer. The seed layer is formed afterthe barrier layer is formed. The seed layer is made of, for example, Cu.The conductor layer 25 may be in contact with the electrode 14.

Next, a conductor layer 26 is formed in the penetration hole 21 so as toform a recessed portion 28, as shown in FIG. 2A. The conductor layer 26may be provided by electroplating using the conductor layer 25 as a seedlayer. The conductor layer 26 may be made of, for example, Cu. Therecessed portion 28 may be formed with an opening expanding toward thesecond surface 20 from a bottom part thereof.

Subsequently, a brazing material layer 30 is formed on the surface ofthe conductor layer 26 in such a manner that the recessed portion 28 isnot completely filled, as shown in FIG. 2B. The brazing material layer30 may be formed by electroplating using the conductor layer 25 as aseed layer after a patterned resist (not shown) is formed on theconductor layer 25. Alternatively, the brazing material may be meltedand ejected or dripped into the recessed portion 28 by an inkjet methodor the like. The recessed portion 28 may be formed with the openingthereof expanding toward the second surface 20 from the bottom surface.The brazing material layer 30 may be made of at least one or pluralmaterials, for example, Sn, Ag, Cu, Zn, In, Bi, Ni, and Pb. As thebrazing material, a brazing material having a lower melting point thanthe conductor layers 25, 26 is employed. The thickness of the brazingmaterial layer 30 is approximately 2 to 10 μm.

Then, the conductor layer 25 formed on the second surface 20 of thesemiconductor substrate 10 is removed, as shown in FIG. 2C. Etching (dryetching or wet etching) may be used to remove the conductor layer 25.

By the above process, a penetration electrode 40 can be formed in thesemiconductor substrate 10 as the first substrate. Although onepenetration electrode is shown in FIGS. 1A to 1D and FIGS. 2A to 2C, thesemiconductor substrate 10 has plural penetration electrodes 40. Thepenetration substrate 40 penetrates the semiconductor substrate from theelectrode 14 on the first surface (main surface) 12 to the secondsurface (back surface) 20. The penetration electrode 40 has the recessedportion 28 on the side of the second surface 20. The recessed portion 28may be formed with the opening thereof expanding toward the secondsurface 20 from the bottom part.

FIG. 3 shows a semiconductor substrate 100 as a second substrate. Thesemiconductor substrate 100 is a semiconductor wafer, but thesemiconductor substrate 100 may be a semiconductor chip. In thesemiconductor substrate 100, at least one integrated circuit (plural ona semiconductor wafer, or one on a semiconductor chip) (for example, acircuit having a transistor and a memory (not shown)) is formed on afirst surface 112 as a main surface. An insulating layer 115 is formedon the circuit. For example, if the base material of the semiconductorsubstrate 100 is Si, the insulating layer may be SiO₂ or SiN. On thesemiconductor substrate 100, electrodes (for example, pads) 114 asplural second electrodes are formed. Each electrode 114 is electricallyconnected to the integrated circuit. Each electrode 114 may be made ofaluminum (Al) or the like. The surface shape of the electrode 114 is notparticularly limited but the shape is often rectangular. If thesemiconductor substrate 100 is a semiconductor wafer, two or more (onegroup of) electrodes 114 are formed in each area that forms pluralsemiconductor chips.

On the semiconductor substrate 100, one or more layers of passivationfilm 116 are formed. The passivation film 116 can be made of, forexample, SiO₂, SiN, polyimde resin or the like. After the passivationfilm 116 is formed to cover the surface of the electrode 114, a portionof the passivation film 116 may be etched to expose a portion of theelectrode 114. Either of dry etching and wet etching may be used forthis etching. In etching the passivation film 116, the surface of theelectrode 114 may be etched.

A protruding electrode 117 is formed on the exposed electrode 114. Theprotruding electrode 117 is formed in a columnar shape protruding in thedirection of the thickness of the semiconductor substrate 100. Theprotruding electrode 117 may be provided by plating (electroplating orelectroless plating). The protruding electrode 117 may be made of, forexample, gold (Au).

FIG. 4 shows the relation between the penetration electrode and theprotruding electrode in this embodiment.

As shown in FIG. 4, the opening width a of the recessed portion 28 ofthe penetration electrode 40 in the semiconductor substrate 10 as thefirst substrate and the distal width b of the protruding electrode 117on the semiconductor substrate 100 as the second substrate are in arelation of a>b. The depth c of the recessed portion 28 of thepenetration electrode 40 in the semiconductor substrate 10 and theheight d of the protruding electrode 117 on the semiconductor substrate100 are in a relation of c<d. The depth c of the recessed portion 28does not include the brazing material layer 30.

As shown in FIG. 5, the semiconductor substrate 10 as the firstsubstrate and the semiconductor substrate 100 as the second substrateare stacked on each other. At this point, the protruding electrode 117on the semiconductor substrate 100 is entered in the recessed portion 28of the penetration electrode 40 in the semiconductor substrate 10. Sincethe distal width b of the protruding electrode 117 on the semiconductorsubstrate 100 is smaller than the opening width a of the recessedportion 28 of the penetration electrode 40 in the semiconductorsubstrate 10, the protruding electrode 117 can be easily entered and thesubstrates can be prevented from being damaged. Moreover, the recessedportion 28 is formed with the opening thereof expanding toward thesecond surface 20 from the bottom part. Thus, the protruding electrode117 on the semiconductor substrate 100 can be easily entered in therecessed portion 28 of the semiconductor substrate 10.

The brazing material layer 30 of the semiconductor substrate 10 and theprotruding electrode 117 on the semiconductor substrate 100 may bejoined by metal-metal junction. A semiconductor device 5 is thusmanufactured.

Since the brazing material layer 30 has a lower melting point than theconductor layers 25, 26 of the semiconductor substrate 10, junction at alower temperature is possible and metal-metal junction can be carriedout easily. Thus, stress can be reduced and therefore reliability ofconnection between the semiconductor substrates can be improved.

Since the height d of the protruding electrode 117 on the semiconductorsubstrate 100 is greater than the depth c of the recessed portion 28 ofthe penetration electrode 40 in the semiconductor substrate 10, anappropriate space can be maintained between the semiconductor substrate10 and the semiconductor substrate 100. Therefore, reliability ofconnection can be improved. The space between the semiconductorsubstrate 10 and the semiconductor substrate 100 (between the secondsurface 20 of the semiconductor substrate 10 and the first surface 112of the semiconductor substrate 100) may be filled with a sealing resin(not shown).

As described above, this embodiment has the following advantages.

The semiconductor substrate 10 as the first substrate is stacked on thesemiconductor substrate 100 as the second substrate. At this point, theprotruding electrode 117 on the semiconductor substrate 100 enters therecessed portion of the penetration electrode 40 in the semiconductorsubstrate 10. Since the distal width b of the protruding electrode 117on the semiconductor substrate 100 is smaller than the opening width aof the recessed portion 28 of the penetration electrode 40 in thesemiconductor substrate 10, the protruding electrode 117 can be easilyentered and the semiconductor substrates 10, 100 can be prevented frombeing damaged. Since the recessed portion 28 is formed to expand towardthe opening end from the bottom, the protruding electrode 117 on thesemiconductor substrate 100 can be easily entered in the recessedportion 28 of semiconductor substrate 10. Moreover, since the height dof the protruding electrode 117 on the semiconductor substrate 100 isgreater than the depth c of the recessed portion 28 of the penetrationelectrode 40 in the semiconductor substrate 10, an appropriate space canbe maintained between the semiconductor substrate 10 and thesemiconductor substrate 100 and reliability of connection can beimproved.

Embodiment 2

FIG. 6 shows the state where semiconductor substrates are stackedaccording to Embodiment 2.

A semiconductor device according to this embodiment will be describedwith reference to FIG. 6. The same components as in Embodiment 1 aredenoted by the same reference numerals and duplicate explanation thereofis not given.

In this embodiment, a semiconductor substrate 200 as a third substrateis stacked between the semiconductor substrate 10 as the first substrateand the semiconductor substrate 100 as the second substrate.

The semiconductor substrate 200 has a penetration electrode 240, whichhas the same configuration as the penetration electrode 40 in thesemiconductor substrate 10. On an electrode 214 of the semiconductorsubstrate 200, one or more layers of passivation film 216 are formed.The passivation film 216 can be made of, for example, SiO₂, SiN,polyimde resin or the like. After the passivation film 216 is formed tocover the surface of the electrode 214, a portion of the passivationfilm 216 may be etched to expose a portion of the electrode 214. Eitherof dry etching and wet etching may be used for this etching. In etchingthe passivation film 216, the surface of the electrode 214 may beetched.

A protruding electrode 217 is formed on the exposed electrode 214. Theprotruding electrode 217 may be provided by plating (electroplating orelectroless plating). The protruding electrode 217 may be made of, forexample, gold (Au).

The penetration electrode 240 in the semiconductor substrate 200 has arecessed portion 228, in which the protruding electrode 117 on thesemiconductor substrate 100 is entered. In the recessed portion 28 ofthe penetration electrode 40 in the semiconductor substrate 10, theprotruding electrode 217 on the semiconductor substrate 200 is entered.Since the distal width of the protruding electrode 117 on thesemiconductor substrate 100 is smaller than the opening width of therecessed portion 228 of the penetration electrode 240 in thesemiconductor substrate 200, and the distal width of the protrudingelectrode 217 on the semiconductor substrate 200 is smaller than theopening width of the recessed portion of the penetration electrode 40 inthe semiconductor substrate 10, the protruding electrodes can be easilyentered and the semiconductor substrates can be prevented from beingdamaged. Moreover, the recessed portion 228 and the recessed portion 28may be formed to expand toward the opening end from the bottom. Thus,the protruding electrode 117 on the semiconductor substrate 100 can beeasily entered in the recessed portion 228 of the semiconductorsubstrate 200, and the protruding electrode 217 on the semiconductorsubstrate 200 can be easily entered in the recessed portion 28 of thesemiconductor substrate 10.

The brazing material layer 30 of the semiconductor substrate 10 and theprotruding electrode 217 on the semiconductor substrate 200, and abrazing material layer 230 of the semiconductor substrate 200 and theprotruding electrode 117 on the semiconductor substrate 100, may bejoined by metal-metal junction. A semiconductor device 6 is thusmanufactured.

Since the brazing material layer 30 has a lower melting point than theconductor layers 25, 26 of the semiconductor substrate 10, and thebrazing material layer 230 has a lower melting point than conductorlayers 225, 226 of the semiconductor substrate 200, junction at a lowertemperature is possible and metal-metal junction can be carried outeasily. Thus, stress can be reduced and therefore reliability ofconnection can be improved.

Since the height of the protruding electrode 217 on the semiconductorsubstrate 200 is greater than the depth of the recessed portion 28 ofthe penetration electrode 40 in the semiconductor substrate 10, and theheight of the protruding electrode 117 on the semiconductor substrate100 is greater than the depth of the recessed portion 228 of thepenetration electrode 240 in the semiconductor substrate 200, anappropriate space can be maintained between the semiconductor substrate10 and the semiconductor substrate 200 and between the semiconductorsubstrate 200 and the semiconductor substrate 100. Therefore,reliability of connection can be improved. The space between thesemiconductor substrate 10 and the semiconductor substrate 200 and thespace between the semiconductor substrate 200 and the semiconductorsubstrate 100 may be filled with a sealing resin (not shown).

As described above, this embodiment has the following advantages inaddition to the advantages of Embodiment 1.

The semiconductor substrate 200 as the third substrate is stacked on thesemiconductor substrate 100 as the second substrate, and thesemiconductor substrate 10 as the first substrate is stacked on thesemiconductor substrate 200. At this point, since the distal width ofthe protruding electrode 217 on the semiconductor substrate 200 issmaller than the opening width of the recessed portion 28 of thepenetration electrode 40 in the semiconductor substrate 10, and thedistal width of the protruding electrode 117 on the semiconductorsubstrate 100 is smaller than the opening width of the recessed portion228 of the penetration electrode 240 in the semiconductor substrate 200,the protruding electrodes can be easily entered and the semiconductorsubstrates 10, 100, 200 can be prevented from being damaged even if thenumber of stacked substrates is greater than in Embodiment 1. Since therecessed portion 228 is formed to expand toward the opening end from thebottom similarly to the recessed portion 28, the protruding electrode117 on the semiconductor substrate 100 can be easily entered in therecessed portion 228 of semiconductor substrate 200, and the protrudingelectrode 217 on the semiconductor substrate 200 can be easily enteredin the recessed portion 28 of the semiconductor substrate 10. Moreover,since the height of the protruding electrode 217 on the semiconductorsubstrate 200 is greater than the depth of the recessed portion 28 ofthe penetration electrode 40 in the semiconductor substrate 10, and theheight of the protruding electrode 117 on the semiconductor substrate100 is greater than the depth of the recessed portion 228 of thepenetration electrode 240 in the semiconductor substrate 200, anappropriate space can be maintained between the semiconductor substrate10 and the semiconductor substrate 200 and between the semiconductorsubstrate 200 and the semiconductor substrate 100. Thus, reliability ofconnection between the semiconductor substrates can be improved.

The invention is not limited to the embodiments and various changes andimprovements can be made to the embodiments. Modifications will bedescribed hereinafter.

Modification 1

FIG. 7, FIG. 8 and FIG. 9 relate to Modification 1. Hereinafter,Modification 1 will be described. The same components as in Embodiments1 and 2 are denoted by the same reference numerals and duplicateexplanation thereof is not given.

FIG. 7 and FIG. 8 show a modification of Embodiment 1.

The distal width b of a protruding electrode 118 on the semiconductorsubstrate 100 and the width e thereof on the side of the electrode 114is in a relation of b<e. In this embodiment, the protruding electrode118 is formed in a truncated cone shape. Since the width e on the sideof the electrode 114 is greater than the distal width b of theprotruding electrode 118, strength of the protruding electrode inrelation to the semiconductor substrate 100 can be improved even if thedistal width is small. Thus, reliability of connection between thesemiconductor substrates can be improved.

As shown in FIG. 8, in a semiconductor device 7, the semiconductorsubstrate 10 with the penetration electrode 40 formed therein is stackedon the semiconductor substrate 100 with the protruding electrode 118formed thereon. Since the distal width of the protruding electrode 118is smaller than the width thereof on the side of the electrode 114, thedistal width of the protruding electrode 118 on the semiconductorsubstrate 100 is sufficiently smaller than the opening width of therecessed portion 28 of the penetration electrode 40 and therefore theprotruding electrode can be easily entered. Thus, the substrates can beprevented from being damaged. Moreover, since the recessed portion 28 isformed with the opening expanding toward the second surface 20 from thebottom part, the protruding electrode 118 on the semiconductor substrate100 can be easily entered in the recessed portion 28 of thesemiconductor substrate 10. The brazing material layer 30 of thesemiconductor substrate 10 and the protruding electrode 118 on thesemiconductor substrate 100 may be joined by metal-metal junction.

Since the height of the protruding electrode 118 on the semiconductorsubstrate 100 is greater than the depth of the recessed portion 28 ofthe penetration electrode 40 in the semiconductor substrate 10, anappropriate space can be maintained between the semiconductor substrate10 and the semiconductor substrate 100 and reliability of connection canbe improved. The space between the semiconductor substrate 10 and thesemiconductor substrate 100 (between the second surface 20 of thesemiconductor substrate 10 and the first surface 112 of thesemiconductor substrate 100) may be filled with a sealing resin (notshown).

FIG. 9 shows a modification of Embodiment 2. In a semiconductor device8, a protruding electrode 218 on the semiconductor substrate 200 as wellas the protruding electrode 118 on the semiconductor substrate 100 has asmaller distal width than a width on the side of the electrode 214. Thebrazing material layer 30 of the semiconductor substrate 10 and theprotruding electrode 218 on the semiconductor substrate 200, and thebrazing material layer 230 of the semiconductor substrate 200 and theprotruding electrode 118 on the semiconductor substrate 100, may bejoined by metal-metal junction. The space between the semiconductorsubstrate 10 and the semiconductor substrate 200 and the space betweenthe semiconductor substrate 200 and the semiconductor substrate 100 maybe filled with a sealing resin (not shown).

As described above, this modification has the following advantages inaddition to the advantages of Embodiments 1 and 2.

Since the distal width of the protruding electrode is sufficientlysmaller than the opening width of the recessed portion of thepenetration electrode, the protruding electrode can be easily enteredand the substrates can be prevented from being damaged. Moreover, sincethe recessed portion is formed to expand toward the opening end from thebottom, the protruding electrode can be easily entered in the recessedportion of the semiconductor substrate.

FIGS. 10A and 10B show a sensor 300 in which the semiconductor deviceaccording to the invention is installed.

FIG. 10A shows an example of configuration of the sensor 300. Thissensor includes a sensor array 310, a row selecting circuit (row driver)320, and a reading circuit 330. The sensor can also include an A/Dconverter unit 340 and a control circuit 350. Using this sensor, forexample, an infrared camera used for a night vision device or the likecan be realized.

In the sensor array 310, plural sensor cells are arrayed (arranged) inbiaxial directions. Plural row lines (word lines, scanning lines) andplural column lines (data lines) are provided. Either the number of rowlines or the number of column lines may be one. For example, if there isonly one row line, plural sensor cells are arrayed in a direction alongthe row line (laterally) in FIG. 10A. Meanwhile, if there is only onecolumn line, plural sensor cells are arrayed in a direction along thecolumn line (longitudinally).

As shown in FIG. 10B, each sensor cell of the sensor array 310 isarranged (formed) at a position corresponding to a point of intersectionbetween each row line and each column line). For example, the sensorcell of FIG. 10B is arranged at a position corresponding to a point ofintersection between a row line WL1 and a column line DL1. Other sensorcells are similarly arranged. The row selecting circuit 320 is connectedto one or plural row lines. The row selecting circuit 320 selects therow lines. By way of example, in the QVGA (320×240 pixels) sensor array310 (focal surface array) as shown in FIG. 10B, the row selectingcircuit 320 sequentially selects (scans) row lines WL0, WL1, WL2, . . .WL239. That is, a signal (word selecting signal) for selecting these rowlines is outputted to the sensor array 310.

The reading circuit 330 is connected to one or plural column lines. Thereading circuit 330 reads the column lines. By way of example, in theQVGA sensor array 310, the reading circuit 330 reads detected signals(detected current, detected charge) from column lines DL0, DL1, DL2, . .. DL319.

The A/D converter unit 340 performs A/D conversion to convert thedetected voltage (measured voltage, achieved voltage) acquired by thereading circuit 330 to digital data. The A/D converter unit 340 thenoutputs A/D-converted digital data DOUT. Specifically, the A/D converterunit 340 is provided with each A/D converter corresponding to each ofthe plural column lines. Each A/D converter performs A/D conversion ofthe detected voltage acquired by the reading circuit 330 in thecorresponding column line. One A/D converter for the plural column linesmay be provided, and the detected voltages of the plural column linesmay be A/D-converted in a time divisional manner using this one A/Dconverter.

The control circuit 350 (timing generator circuit) generates variouscontrol signals and outputs the control signals to the row selectingcircuit 320, the reading circuit 330, and the A/D converter unit 340.For example, the control circuit 350 generates and outputs a controlsignal for charge and discharge (reset). Alternatively, the controlcircuit 350 generates and outputs a signal to control timing of eachcircuit.

Examples of an electronic device according to the invention may includea personal computer 400 shown in FIG. 11 and a mobile phone 500 shown inFIG. 12 and the like. In all these devices, the semiconductor devicedescribed in the embodiments is installed as an internal device.

The invention is not limited to the embodiments and variousmodifications can be made. For example, the invention includessubstantially the same configurations as the configurations described inthe embodiments (for example, configurations with the same functions,methods and results, or configurations with the same objects andresults). The invention also includes the configurations described inthe embodiments in which non-essential parts are replaced. The inventionalso includes configurations having the same effects and advantages asthe configurations described in the embodiments, or configurations thatenable achievement of the same objects. The invention also includesknown techniques added to the configurations described in theembodiments.

The entire disclosure of Japanese Patent Application No. 2011-037969,filed Feb. 24, 2011 is expressly incorporated by reference herein.

What is claimed is:
 1. A semiconductor device comprising: a firstsubstrate having a first electrode formed on a first surface, and apenetration electrode formed in a hole reaching the first electrode froma second surface opposite to the first surface; and a second substratehaving a protruding electrode connected to the penetration electrode;wherein the penetration electrode has a recessed portion on the side ofthe second surface, and a bottom part of the recessed portion issituated between the first surface and the second surface of the firstsubstrate, the protruding electrode is entered in the recessed portionso that a distal end of the protruding electrode has contact with thebottom part of the recessed portion of the penetration electrode, andthe contact is located inside the first substrate, an opening width a ofthe recessed portion and a distal width b of the protruding electrodeare in a relation of a>b so that an inner surface of the recessedportion is spaced apart from an outer surface of the protrudingelectrode, the penetration electrode is made of two or more kinds ofmaterial, and a surface of the recessed portion is made of a materialhaving the lowest melting point of the two or more kinds of material,and the material with the lowest melting point and the protrudingelectrode are joined by metal-metal junction.
 2. The semiconductordevice according to claim 1, wherein a depth c of the recessed portionin the first substrate and a height d of the protruding electrode on thesecond substrate are in a relation of c<d.
 3. The semiconductor deviceaccording to claim 1, wherein the recessed portion in the firstsubstrate has an opening expanding toward the second surface from thebottom part.
 4. The semiconductor device according to claim 1, whereinthe material with the lowest melting point is a brazing material.
 5. Thesemiconductor device according to claim 1, wherein the distal width b ofthe protruding electrode formed on the second substrate and a proximalwidth e of the protruding electrode are in a relation of b<e.
 6. Thesemiconductor device according to claim 1, wherein the first surface iscovered with a passivation film, and a portion of the first electrodesis exposed from the passivation film, and the portion of the firstelectrode exposed from the passivation film has a surface thereofetched.
 7. A sensor comprising the semiconductor device according toclaim
 1. 8. An electronic device comprising the semiconductor deviceaccording to claim
 1. 9. An electronic device comprising the sensoraccording to claim
 7. 10. The semiconductor device according to claim 1,wherein an entire structure of the penetration electrode is locatedbetween the first surface and the second surface.
 11. The semiconductordevice according to claim 1, further comprising: a third substratehaving third and fourth surfaces opposite to each other, the thirdsubstrate having a second electrode formed on the third surface, and asecond penetration electrode formed in a second hole reaching the secondelectrode from the fourth surface; and a second protruding electrodethat is formed on the first electrode of the first substrate, whereinthe second penetration electrode has a second recessed portion on theside of the fourth surface, and a bottom part of the second recessedportion is situated between the third surface and the fourth surface, astacking order of the semiconductor device from a bottom to a top is asfollows: the second substrate, the protruding electrode, the penetrationelectrode formed in the first substrate with the recessed portioncontacting the protruding electrode, the first electrode formed on thefirst surface of the first substrate, the second protruding electrodeformed on the first electrode, the second penetration electrode formedin the third substrate with the second recessed portion contacting thesecond protruding electrode, and the second electrode formed on thethird surface of the third substrate.
 12. A semiconductor devicecomprising: a first substrate; a first electrode that is disposed so asto cover the first substrate; a penetration electrode that is disposedin a hole of the first substrate, the hole penetrating the firstsubstrate, the penetration electrode being electrically connected to thefirst electrode; a second substrate; and a protruding electrode thatprotrudes from the second substrate, wherein the penetration electrodehas a first part and a second part, and a melting point of the secondpart is lower than a melting point of the first part, and the protrudingelectrode is entered in the hole, and the protruding electrode and thesecond part are joined by metal-metal junction.
 13. The semiconductordevice according to claim 12, wherein an opening width a of a recessedportion of the penetration electrode and a distal width b of theprotruding electrode are in a relation of a>b.
 14. The semiconductordevice according to claim 12, wherein the second part contains a brazingmaterial.